Gliederung

Background

In recent years potent modern drugs have been approved for over the counter (OTC) use. Thus, it has become relevant to assess whether these drugs are used according to the directions for use, as outlined in the patient information leaflet (PIL), and safe. The methodology used for two pharmacy-based cohort studies will be discussed and data about the appropriateness of use will be presented.

Methodology

Every customer who bought a nicotine patch (study A) or a low dose NSAID (study B) was eligible. To assure that the real conditions of everyday use of these drugs were evaluated it was left to the individual pharmacist if and to what degree the customer was informed about the appropriate use. Only after buying the nicotine patch, the customer was asked to give written consent to participate.

Data were collected at baseline and at appropriate time points thereafter.

All data were collected by SAQs.

Results

Study A, which was done first, recruited 633 participants by 220 pharmacies. The response rate after 24 weeks was 55%. Study B with 446 participants had a response rate after 20 days of 97%. In study A 16.6% and study B 11% of the patients did not use the purchased drug. 81% of the participants of study A indicated to have been informed by the pharmacist (study B: 72%). With regard to dosage and duration (A: 87%, B: 20%), contraindications (A: 53%, B: 28.3%), and interactions (A: 39%, B: 12%) information was given. The majority of participants (A: 91.5%, B: 80%) indicated having read the PIL.

Of the participants, 63% (A) and 95.2% (B) complied with the recommend length of drug use. In study B, 3.6% used higher dosages than recommended. In study A, there was a tendency to use less dosage than recommended as the patch was renewed daily by 85% (day 14) and 27% (week 12), only.

Labelled contraindications were ignored by 4% (A) and 1% (B).

There were no serious adverse drug reactions.

Discussion and Conclusion

Pharmacy-based cohort studies evaluating appropriateness of use of OTC drugs are feasible. Extra efforts are needed to keep lost to follow-up rates low and data quality high. Compliance with the directions for use was not perfect, but did not result in any serious risks. Higher dosages than recommended are rare, whereas extensions of treatment duration are more common.